English has evolved to become the language of the world. Today, there are some 2 billion English speakers on the planet, and as a result the language continues to change in cunning, playful and exciting ways.
The story of English starts, if it starts anywhere, in a Suffolk field in the 5th century. This is where the Undley bracteate - a beautiful gold pendant - was discovered. On the pendant is what we believe is the first sentence written in English. Although it is in runes (as opposed to the Latin-based alphabet we use today), the inscription is recognisably English, saying something about a "reward for a kinsman".
In our book, A History of the English Language in 100 Places, we tell this story and 99 others, taking readers on a giddy journey across the globe. It is truly an epic and international tale: our tour takes in places from Winchester to Los Angeles; Singapore to Swarthmore.
The culmination of this adventure is in Vienna, where one of the largest searchable databases of spoken English has been created in collaboration with the University of Oxford. The significance of this collection is that it explores English as a lingua franca, a common global language. This is important because English is now global - some time in the last decade, there was a magical moment when the number of people who speak English as a second language overtook the number who call it their mother tongue.
English has borrowed words from more than 350 languages, and many more languages have borrowed from English. If a Spanish pilot wants to speak to a Swedish air-traffic controller, he will use English. Universities and schools in non-English-speaking countries are increasingly opting for English as the medium of instruction. Whether we are considering business, scientific papers, snail mail or email, English is ubiquitous.
For any teacher in an English-speaking country, the strength of the language creates a dilemma. It invites us to be lazy with regard to learning foreign languages, while equipping our students with a natural advantage over international competitors.
There are other, subtler issues. As native speakers, we are less likely to master the grammar of our own language, which may be a factor in our poor Programme for International Student Assessment (Pisa) literacy results. English is also morphing rapidly as a result of social media, with the introduction of words such as "innit", "ata2ud" (attitude) and "awcigo" (and where can I get one?).
As long ago as March 2003, The Daily Telegraph ran the headline: "Girl writes English essay in phone text shorthand". The 13-year-old student submitted her essay - at a state secondary school in west Scotland - with an explanation that she found her shorthand "easier than standard English".
Such textspeak worries some teachers. So does its cousin, teenspeak, the label that has been applied to the rapidly changing contemporary English used by young people. It abounds with exclamations: the likes of "deezam", "OMG", "ooowee", "yo" and "shut up!" (which means, in teenspeak, the opposite of its adult equivalent - it's an affirmation).
Exciting as these changes are to linguists, they present a huge challenge to teachers in the UK. What kind of English should they teach? The problem is compounded because, in the 1970s, the study of grammar was unhelpfully dropped from the state school curriculum in England and Wales. Children were expected to find their own way to Standard English. It is worth noting that many of them did, but the rights and wrongs of grammar were nevertheless called into question.
For the foreseeable future, English teachers - and indeed, all teachers - in the UK should continue to teach Standard English. Not least because it helps children aspire to and obtain well-paid jobs.
At the same time, English teachers should discuss the huge variety of Englishes in the world. In the British Isles alone, there may be as many as 700 different accents with some 100 dialects underlying them. There is no need to teach those dialects; it would be impossible to choose which to study. But there is every need to treat them all with respect. Dialect writing, especially poetry and song, needs to be celebrated.
The situation is similar in English-speaking countries outside the British Isles. Being able to read rapidly and write effectively is key. Children need to know a common form of English and effectively there are only two: Standard American English and Standard British English. Anyone who knows one will be able to read the other, although not necessarily write it. There are 500 spelling differences, many vocabulary variations and some subtle grammatical departures.
The choice between Standard American and Standard British English is usually a political one. Countries that were once part of the British Empire often choose to use the British standard, as in the cases of Australia, Barbados, India, South Africa and New Zealand. In Canada, both are accepted. Singapore and many Pacific Island nations tend towards the American standard. It is worth noting - with an eye to the future - that American English is the dominant form on the internet and in popular culture.
But in every classroom, everywhere in the world, teachers must recognise that standard forms are artificial constructs. The vital life of the language is in the home and on the street.
So is the grammatical soul of the English language really at risk? Should we be worried? The threat is certainly considerable but we are not afraid. First of all, if we look across the world of published books and major newspapers, the English language is holding up very well. Second, we must not expect language to be static. It always changes, even without external influences, and this is not evidence of decline. Third, the English grammar we inherited from Dr Johnson, the man credited with compiling the first English dictionary, was always going to be a compromise; an honest attempt to describe best practices rather than a precise rule book.
Clearly, if our children are to make an impression in the world, they will need to be able to use correct English. Nonetheless, "correct English" is a limited and limiting concept in relation to the age-old story of English grammar, which has evolved steadily since it first arrived on these shores. It has changed its entire form every 300 years (on average) and it continues this evolution as we use it today.
Bill Lucas and Christopher Mulvey are trustees of the English Project and authors of A History of the English Language in 100 Places.
An English odyssey: language on the map
In their book A History of the English Language in 100 Places, Bill Lucas and Christopher Mulvey journeyed to some of the key locations that shaped the English language as we know it. These included:
Winchester, England Where Alfred the Great became the first king to insist on the use of English by his scribes.
Bruges, Belgium Location of the first printing press to make books in English.
Hampton Court, England Where the King James Bible was commissioned.
Jamestown, Virginia, US The first permanent settlement in America, from where English spread across the US.
Lichfield, England Birthplace of Dr Samuel Johnson, author of the first dictionary.
New Orleans, Louisiana, US A key area in the development of African-American English.
Portland Place, England The home of BBC English.
Singapore Birthplace and home of "Singlish".
Geneva, Switzerland Where Tim Berners-Lee invented the World Wide Web.
Edinburgh, Scotland The city in which JK Rowling wrote the first Harry Potter book.
Swarthmore, Pennsylvania, US Internationally recognised as the birthplace of blogging.
Help your students to separate their apples from their pears with this history of cockney rhyming slang.
A simple lesson dissecting the difference between verbs, nouns and adjectives.
This colourful resource teaches children to build sentences using Lego.
Can your students identify non-standard English? Try them with this tutorial.
A handy place mat will help students with spelling, punctuation and grammar.
Brush up on your own grammar with teacher-friendly flashcards.